Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L51/00—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
  • C08L51/04—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers grafted on to rubbers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L77/00—Compositions of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Compositions of derivatives of such polymers
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S525/00—Synthetic resins or natural rubbers -- part of the class 520 series
  • Y10S525/942—Polymer derived from nitrile, conjugated diene and aromatic co-monomers

Definitions

• Polyamide resins have excellent abrasion resistance, electrical properties, mechanical strength and chemical resistance. Therefore, their molded products have been used for various mechanic parts as engineering plastics. However, they have drawbacks such as large water absorbance, low heat resistance and low impact resistance, particularly low notched impact strength. Further, they also have drawbacks that they are inferior in rigidity upon absorption of moisture and in molding processability.
• ABS resin acrylonitrile-butadiene-styrene copolymer
• a blend resin composition e.g. Japanese Examined Patent Publication No. 23476/1963.
• ABS resin acrylonitrile-butadiene-styrene copolymer
• such a blend resin composition of a polyamide resin with an ABS resin is inferior in the compatibility, and when formed into a molded product, it brings about drawbacks such that a lamellar peeling phenomenon is likely to result due to inadequate compatibility, and the mechanical strength is likely to substantially deteriorate e.g. as lacking in toughness.
• the present inventors have conducted extensive research with an aim to solve the above-mentioned various drawbacks inherent to the conventional resin compositions comprising a polyamide resin and a rubber-modified styrene-type graft copolymer and have finally arrived at the present invention. Namely, it is an object of the present invention to provide a resin composition capable of providing a molded product having excellent heat resistance and particularly remarkably improved impact resistance, by blending a graft copolymer obtained by graft polymerizing a monomer mixture containing an N-substituted maleimide monomer to a conjugated diene rubber, with a polyamide resin.
• a resin mixture comprising from 20 to 80% by weight of a polyamide resin (A) and from 20 to 80% by weight of a graft copolymer resin (B) obtained by graft polymerizing from 30 to 65 parts by weight of a monomer mixture comprising from 30 to 80% by weight of an aromatic vinyl monomer, from 5 to 65% by weight of an N-substituted maleimide monomer and from 0 to 40% by weight of other vinyl monomer copolymerizable with these monomers (provided that the total amount of said monomer mixture is 100% by weight) to from 35 to 70 parts by weight of a conjugated diene rubber;
• the polyamide resin (A) constituting the resin composition of the present invention is an injection-moldable conventional nylon-type thermoplastic resin.
• polyamide resin (A) include nylons called by common names such as nylon 6, nylon 66, copolymer nylon (copolymer of caprolactam with hexamethylenediamine adipate), nylon 610, nylon 612, nylon 12 and nylon MXD6 (condensation polymer of m-xylylenediamine with adipic acid) and copolymers comprising these nylons as main components, and mixtures thereof.
• nylon 6, nylon 66 and copolymer nylon, and a mixture thereof are particularly preferred.
• the graft copolymer resin (B) constituting the resin composition of the present invention is obtained by graft polymerizing from 30 to 65 parts by weight of a monomer mixture (I) comprising from 30 to 80% by weight of an aromatic vinyl monomer, from 5 to 65% by weight of an N-substituted maleimide monomer and from 0 to 40% by weight of other vinyl monomer copolymerizable with these monomers (provided that the total amount of the monomer mixture is 100% by weight) to from 35 to 70 parts by weight of a conjugated diene rubber.
• This graft copolymer resin (B) is an impact resistant resin having good compatibility with the polyamide resin (A) and excellent heat resistance, since it contains an N-substituted maleimide monomer component.
• the conjugated diene rubber as a component constituting the graft copolymer resin (B) is a rubbery polymer containing at least 50% by weight of a conjugated diene monomer component such as butadiene, isoprene or chloroprene and having a glass transition temperature of not higher than 0° C.
• a conjugated diene rubber include known synthetic rubbers such as butadiene rubber (BR), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR) and isoprene rubber (IR).
• This conjugated diene rubber preferably has an average particle size within a range of from 0.1 to 0.5 ⁇ m in its latex form as dispersed in water. If the average particle size is less than 0.1 ⁇ m, no adequate improvement in the impact resistance will be observed in the resulting graft copolymer resin. If the average particle size exceeds 0.5 ⁇ m, emulsion graft polymerization tends to be difficult, and the stability of the rubber latex tends to deteriorate.
• the average particle size of e.g. a conjugated diene rubber dispersed in water is meant for a weight average particle size as measured in a system of latext dispersed in water of 23° C. by Coulter® Nano-SizerTM manufactured by Coulter Electronics Ltd.
• aromatic vinyl monomer as a component of the above monomer mixture (I) include styrene, an ⁇ -alkylstyrene such as ⁇ -methylstyrene, a ring-substituted alkylstyrene such as p-methylstyrene and vinyl naphthalene. These monomers may be used alone or in combination as a mixture of two or more.
• the proportion of the aromatic vinyl monomer in the monomer mixture (I) is from 30 to 80% by weight. If the proportion exceeds 80% by weight, the heat resistance of the resulting resin tends to be poor, or the compatibility with the polyamide resin (A) tends to be inferior. If the proportion is less than 30% by weight, the properties of the graft polymerized resin tend to change, whereby the type of other copolymer resin to be blended will be limited, such being undesirable.
• the N-substituted maleimide monomer may be at least one monomer selected from the group consisting of N-aromatic maleimides such as N-phenylmaleimide, N-(o-methylphenyl)maleimide, N-(m-methylphenyl)maleimide and N-(p-methylphenyl)maleimide, N-alicyclic alkylmaleimides such as N-cyclohexylmaleimide and N-aliphatic alkylmaleimides having from 1 to 10 carbon atoms. Among them, N-phenylmaleimide is particularly preferred.
• the N-substituted maleimide monomer is contained in the monomer mixture (I) in an amount within a range of from 5 to 65% by weight. If the content exceeds 65% by weight, the copolymer resin tends to be non-uniform, whereby the desired graft copolymer resin will hardly be obtained. If the content is less than 5% by weight, the heat resistance of the graft copolymer resin will be inadequate, and the compatibility with the polyamide resin (A) tends to be inferior, and thus no adequate effect by the copolymerization of the N-substituted maleimide monomer will be obtained.
• a vinyl cyanide monomer such as arylonitrile or methacrylonitrile, a carboxylic acid-containing vinyl monomer such as acrylic acid, methacrylic acid, itaconic acid or fumaric acid, a metal salt such as an alkali metal salt or an alkaline earth metal salt of the carboxylic acid-containing vinyl monomer, a carboxylate-containing vinyl monomer such as an arylate, a methacrylate, an itaconate, a fumarate or a maleate having an alkyl group of from 1 to 10 carbon atoms, a cycloalkyl group, a benzyl group or a phenyl group, and an ⁇ , ⁇ -unsaturated dicarboxylic anhydide such as maleic anhydride, may be mentioned.
• These monomers may be used alone or in combination as a mixture of two or more.
• Such a vinyl monomer copolymerizable with these monomers is contained in the monomer mixture (I) in an amount of not higher than 40% by weight. If the amount exceeds 40% by weight, not only the reaction condition for the graft polymerization will have to be changed, but also the physical properties of the graft polymerized resin will be changed, such being undesirable.
• the graft copolymer resin (B) in the present invention is prepared by mixing the above monomer mixture (I) to from 35 to 70 parts by weight of the above conjugated diene rubber in an amount within a range of from 30 to 65 parts by weight and polymerizing the mixture for graft polymerization. If the proportions in parts by weight of the conjugated diene rubber and the monomer mixture (I) are outside the above ranges, it will be likely that the copolymer of the monomer mixture (I) can not cover the surface of the conjugated diene rubber particles, or the proportion of the conjugated diene rubber in the graft copolymer resin will be too small, such being undesirable.
• an emulsion polymerization method for this graft polymerization, an emulsion polymerization method, a suspension polymerization method, a solution polymerization method or a bulk polymerization method may be employed.
• an emulsion polymerization method it may be conducted by a usual emulsion polymerization method wherein water is used as the medium.
• the graft polymerization is continued by a method other than the emulsion polymerization method, it is advisable that firstly the surface of the conjugated diene rubber particles is covered with the graft copolymer so that the rubber particles can be dispersed by themselves into the monomer mixture (I), and then the emulsion system is changed to a suspension system, a solution system or a bulk polymerization system to continue the graft polymerization.
• the polymerization system After the completion of the graft polymerization, the polymerization system is subjected to a suitable combination of known after-treatments, such as distillation, salting out, separation, washing, drying, mixing and pelletizing, to obtain a graft copolymer resin (B).
• a suitable combination of known after-treatments such as distillation, salting out, separation, washing, drying, mixing and pelletizing
• the resin mixture constituting the composition of the present invention comprises from 20 to 80% by weight of the polyamide resin (A) and from 20 to 80% by weight of the graft copolymer resin (B). Particularly preferred is a mixture comprising from 30 to 70% by weight of the polyamide resin (A) and from 30 to 70% by weight of the graft copolymer resin (B). If the blending ratio is outside the above range, the mechanical strength such as impact resistance and the physical properties such as heat resistance and molding processability of the resin compostion thereby obtained, tend to be poor.
• the resins (A) and (B) may be incorporated in any manner so long as they are contained finally within the above ranges in the resin composition of the present invention.
• the copolymer resin (C) constituting the resin composition of the present invention comprises from 30 to 80% by weight of an aromatic vinyl monomer component, from 5 to 65% by weight of an N-substituted maleimide monomer component and from 0 to 40% by weight of other vinyl monomer component copolymerizable with these monomers (provided that the total amount of the monomer components is 100% by weight).
• the copolymer resin (C) is a thermoplastic hard resin having excellent heat resistance, since it contains an N-substituted maleimide monomer component.
• copolymer resin (C) is added at the time of mixing the polyamide resin (A) with the graft copolymer resin (B) to improve the dispersibility and the compatibility of two resins (A) and (B), whereby the mechanical strength such as impact resistance and the properties such as heat resistance will be improved.
• the aromatic vinyl monomer component, the N-substituted maleimide monomer component, and other vinyl monomer component copolymerizable with these monomers, as the components constituting the above copolymer resin (C) are the same as the respective vinyl monomers described above as the components of the monomer mixture (I).
• the proportions of the components constituting the copolymer resin (C) are within the above ranges, and if they are outside the respective ranges, the heat resistance of the resulting resin composition or the compatibility between the resins tends to deteriorate, such being undesirable. Further, it is particularly preferred that a part of the exemplified other vinyl monomer component constituting the copolymer resin (C) is an ⁇ , ⁇ -unsaturated dicarboxylic anhydride, and this ⁇ , ⁇ -unsaturated dicarboxylic anhydride component is contained in the resin (C) within a range of from at least 0.01 to 30% by weight.
• the copolymer resin (C) containing the ⁇ , ⁇ -unsaturated dicarboxylic anhydride component within this range is effective for dispersing the polyamide resin (A) and the graft copolymer resin (B) with particularly excellent compatibility, and it is thereby possible to produce a resin composition having particularly high impact resistance.
• the process for production of the above copolymer resin (C) includes the following two methods, and either method may be employed.
• the copolymer resin (C) When the copolymer resin (C) is prepared by this method, it can be prepared at the same time as the production of the graft copolymer resin (B) in the same polymerization system, or it can be prepared separately by setting up its own polymerization method and condition.
• the actual operation may be conducted by bulk polymerization, solution polymerization, suspension polymerization and/or an emulsion polymerization. Either batch system or continuous system may be employed. Such polymerization methods and systems may optionally be combined. Further, for the treatment after completion of the copolymerization operation, various conventional operational units such as extraction, deposition, distillation, flocculation, filtration, washing, drying and pelletizing may be employed in a proper combination. The copolymer can be obtained by such aftertreatments.
• copolymer resins (C) prepared by these methods (1) or (2) may be used alone or in combination.
• the copolymer resin (D) constituting the resin composition of the present invention is a thermoplastic resin comprising from 60 to 90% by weight of an aromatic vinyl monomer component, from 0 to 40% by weight of vinyl cyanide monomer component and from 0 to 40% by weight of methylmethacylate component.
• the aromatic vinyl monomer and the vinyl cyanide monomer which are components constituting the copolymer resin (D) are the same as respective vinyl monomers exemplified as the components of the monomer mixture (I) in the graft copolymer resin (B).
• the operations of the components constituting the copolymer resin (D) are as defined above. If the proportions are outside these ranges, the properties of the copolymerized resin will change, and the compatibility with other resins to be mixed tends to deteriorate and the heat or impact resistance of the desired resin composition tends to be low, such being undesirable.
• copolymer resin (D) may be prepared at the same time as the polymerization of the graft copolymer resin (B) and/or the copolymer resin (C) in the same polymerization system, or may be prepared separately by setting up its own polymerization method and conditions.
• a mixture of one or more kinds of these copolymer resins in the form of powder, beads, flakes or pellets may be mixed and kneaded by an extruder such as a single-screw extruder or a twin-screw extruder, or by a kneading machine such as a Banbury mixer, a pressure kneader or a twin roll mill, to obtain a resin composition.
• an extruder such as a single-screw extruder or a twin-screw extruder
• a kneading machine such as a Banbury mixer, a pressure kneader or a twin roll mill
• the resin composition thereby obtained may be used for molding as it is or after being dried.
• a lubricant such as a lubricant, a releasing agent, a coloring agent, an antistatic agent, a flame retardant, a ultraviolet absorber, a light stabilizer, a heat stabilizer, a filler or a nucleating agent may be added in a suitable combination to the resin composition of the present invention in an amount and of the type not adversely affect the nature of the resin.
• a fiber-like reinforcing agent such as glass fiber, metal fiber, carbon fiber or potassium titanate whiskers, talc, clay, potassium carbonate, mica, glass flake, milled fiber, metal flake and metal powder, may be mentioned. These fillers may be used alone or in combination as a mixture of two or more.
• the resin composition of the present invention may be formed into shaped products such as automobile parts, electrical parts or industrial parts by various molding methods such as injection molding, extrusion molding or compression molding, which are useful for applications where excellent heat and impact resistance is required.
• the resin composition of the present invention obtained by blending the copolymer resin (C) containing an N-substituted maleimide monomer component to the resin mixture comprising the polyamide resin (A) and the graft copolymer resin (B) containing an N-substituted maleimide monomer component, can be used as a thermoplastic resin material having extremely high impact resistance, particularly excellent notched impact strength, which has not been expected before.
• the resin composition of the present invention shows good compatibility and gives a molded product having excellent heat resistance and the mechanical strength, since the graft copolymer resin (B) containing an N-substituted maleimide monomer is blended therein.
• KPS potassium persulfate
• the latex obtained was dropwise added to a 4% magnesium sulfate aqueous solution heated to 95° C. for salting out, followed by dewatering and drying to obtain a maleimide graft copolymer resin (B) in a powder form.
• a polymerization reactor equipped with a refluxing condenser, a stirrer and a monomer supply device, 100 parts of deionized water having 0.03 part of a polyvinyl alcohol-type suspending agent dissolved therein was charged.
• a monomer mixture comprising 30 parts of St, 15 parts of AN and 20 parts of N-PMI was further charged together with 0.4 part of terpinolene (chain transfer agent).
• the internal temperature was maintained at 60° C. under a nitrogen stream under stirring, and 0.06 part of ⁇ , ⁇ '-azobisisobutyronitrile was added as a polymerization initiator to initiate the polymerization reaction.
• a polyvinyl alcohol-type suspending agent was added to the polymerization reactor, and after 30 minutes, 60 minutes, 90 minutes and 120 minutes from the initiation of the polymerization reaction, 0.0225 part of a polyvinyl alcohol-type suspending agent was added to the polymerization reactor. During this period, the temperature of the polymerization system was maintained at 60° C.
• stearyl- ⁇ -(3,5-di-t-butyl-4-hydroxyphenyl)propionate (antioxidant) and magnesium stearate (lubricant) were blended in an amount of 0.1 part, respectively, per 100 parts by weight of the copolymer resin, and the blend was kneaded by an extruder provided with a vent while degassing and then pelletized to obtain a copolymer resin (C)-I.
• the suspension system was heated to 155° C., and 90 parts of aniline and 10 parts of 25 wt% aqueous ammonia were added thereto.
• the suspension system was stirred at the same temperature for 120 minutes to conduct the polymer imidization reaction.
• the suspension system was cooled, followed by filtration, washing with water and drying to obtain a copolymer in the form of beads.
• the beads copolymer was pelletized by a single-screw extruder.
• the pellets were analyzed by NMR and found to be a mixture of a copolymer resin (C)-II comprising 58.8% by weight of a styrene component, 38.2% by weight of an N-phenylmaleimide component, 1.4% by weight of a maleimide component and 1.6% by weight of a maleic anhydride component and a copolymer resin (D) comprising 73.8% by weight of a styrene component and 26.2% by weight of an acrylonitrile component, the composition being 76% by weight of the copolymer resin (C)-II and 24% by weight of the copolymer resin (D).
• Nylon 6 (NOVAMID® 1020, manufactured by Mitsubishi Chemical Industries Limited) as the polyamide resin (A), the graft copolymer resin (B), the copolymer resin (C) and the copolymer resin (D), which were prepared by the methods disclosed in Preparation Example, were weighed in the proportions (parts) as identifed in Table 1, and they were mixed in a tumbler. The mixture thereby obtained was kneaded by a single-screw extruder equipped with a vent while removing a volatile component, to obtain pellets of the resin composition.
• NOVAMID® 1020 manufactured by Mitsubishi Chemical Industries Limited
• the pellets of this resin composition was formed by an injection molding into test pieces for the measurement of the physical properties. With respect to the molded test pieces, the tensile strength, the Izod impact strength (notched), the Vicat softening point and the melt flow rate were measured, respectively. The results are shown in Table 1.
• the resin composition of the present invention has high Izod impact strength (notched) and high Vicat softening point, since the graft copolymer resin (B) containing a component of N-phenylmaleimide is incorporated therein. (Examples 1 to 7) Among them, the resin composition having the copolymer resin (C) containing a component of N-phenylmaleimide blended in the optimum amount, has as extremely high Izod impact strength (notched), whcih has not been expected before, (Examples 2 to 6).
• resin compositions with the proportions outside the ranges of the present invention are ill-balanced in the above-mentioned properties, and have drawbacks that at least one physical property is bad, (Comparative Examples 1 to 3).

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Citations (6)

• 1986
  • 1986-12-29 JP JP61310120A patent/JPH0725982B2/ja not_active Expired - Lifetime
• 1988
  • 1988-05-27 US US07/199,850 patent/US4981906A/en not_active Expired - Fee Related

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